460 ADDITIONAL NOTES 



bulacra in this region of the test ; these, however, are limited to the base, for on the sides 

 (fig. 1 c) and upper surface (fig. 1 a) there is only a single row of tubercles ; at the base 

 of the ambulacral areas the tubercles are larger, and the pores, closely packed together, 

 lie obliquely across the zone in groups of threes (fig. 1 d). 



Stratigrapliical distribution. — I know this urchin from the Pea Grit and Oolite Marl, 

 •zone of Ammonites Murcldsonce, Inferior Oolite, from Crickley Hill, and the Seven Springs, 

 aiear Cheltenham. 



The specimen from the Great Oolite near Cirencester was almost entirely denuded of 

 its test, but the position of the tubercles near the poriferous zones served to identify the 

 species. This specimen was collected by Mr. Bravender, and kindly communicated for this 

 work. 



The Cornbrash specimen is circular, and much more depressed than any of the other 

 varieties. It has enabled us to describe and figure correctly the entire external structure 

 of this singular form. 



Dr. Smith's specimen had a very marked pentagonal base, and although this character 

 is absent in most of the specimens I have examined, still I have found the pentagonal out- 

 line to characterise one specimen from the Pea Grit and one from the Oolite Marl. 



M. Cotteau recognised the resemblance which exists between this urchin and Pedina 

 Bakeri, Wr., but the absence of a good figure of Pedina 8mithii, Porbes, rendered it 

 impossible for that learned author to discover the identity of his Pseudopedina Nodoti with 

 Pedina SmitJdi. The excellent figures which I have now given will show that the French 

 and English forms belong to the same species. M. Cotteau found the specimen figured by 

 him in the Museum of Dijon ; it was obtained from the Etage Bathonien, route de Pauge 

 (Cote-d'Or), where it is very rare. 



SALENIAD/E. 



AcROSALENiA PUSTULATA, Forbes. Supplemental to pages 242-245. 



I am indebted to Frederick Bravender, Esq., for the following notes on the discovery, in 

 December, 1858, of a bed of marl in the Great Oolite near Cirencester, which contained 

 immense numbers of Acrosalenia ^ustulata. He remarks — " We have discovered an 

 extraordinary urchin-bed in a quarry near the town, but unfortunately the urchins are 

 nearly all of the same sort. They occur in a marly bed in the Great Oolite, about four inches 

 above the clay bed. I have now as many as 500 specimens, and might have got 1000 

 if I wanted them, as they were as thick as bees in a hive. If the bed extends any further, 

 which will be ascertained when the quarrymen proceed, any quantity might be obtained. 



The following section will afi'ord an idea of the relative position of this marly vein 

 with its Acrosolenice. 



